OFFICE OF
CHEMICAL SAFETY AND

POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

PC Code: 024875

MEMORANDUM DP Barcode: 427622

DATE: June 26, 2015

SUBJECT: Response to the Initial 60 -Day Public Comment on: “ Registration Review: Draft Problem Formulation for Envi ronmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for Spiromesifen (2/20/15; PC Code 024875; DP Barcode 422437) ”

TO: Jolene Trujillo, Chemical Review Manager Jill Bloom, Team Leader Linda Arrington, Branch Chief Risk Management and Implementation Branch 5 (RMIBV)

Pesticide Re-evalua tion Division (7508P)

FROM: Karen Milians, Ph.D., Chemist Andrew Sayer, Ph.D., Biologist

Environmental Risk Branch IV

Environmental Fate and Effects Division Office of Pesticide Programs

REVIEWED

BY: Jim Carleton, Ph.D., Senior Scientist Catherine Aubee, Senior Scientist

Environmental Risk Branch IV

Environmental Fate and Effects Division Office of Pesticide Programs

APPROVED

BY: Jean Holmes, DVM, MPH, Branch Chief

Environmental Risk Branch IV

Environmental Fate and Effects Division Office of Pesticide Programs

The Environmental Fate and Effects Division (E FED) has reviewed the public comments on the Preliminary Work Plan for Registration Review of spiromesifen, including the draft problemPage 2 of 3 formulation 1 for environmental fate, ecological ris k, endangered species and human health drinking water exposure assessments. Comments were received from Bayer Crop Science and a specific comment is addressed in this response.

In the following section, the specific comment is summarized in italics and is then followed by EFED’s response.

1. Environmental Safety (page 3): a) “ Bayer comment : Bayer has additional re ports to submit to EPA See appendix 2. 1. Formulation study, Green algae. EPA Guideline 850.5400. 2. Formulation study, Lab study with Bombus terrestris (L). EPA Guideline 850.SUPP. 3. Formulation study, Aquatic field study; Freshwater microcosm. EPA Guideline

850.1950”

EFED’s response: EFED acknowledges Bayer’s intention to s ubmit additional reports and will review the

submission when it is received.

2. Environmental Safety (page 3: b) “The trout ELS (MIRO 45819627) will be ame nded to include these endpoints. Bayer

looked into the raw data and the time to hatch and time to swim up data was collected. It is unclear how it was omitted from the final re port. Bayer is working with the contract lab to amend the report and it will be submitted to EPA in 2015.”

EFED’s response: EFED acknowledges Bayer’s intention to submit additional data on time-to-hatch and time-to-swim up and will review the amended report when it is submitted.

3. Drinking Water (page 4):

a) “BCS considers the total toxic residues (TTR) method previously used by EFED for groundwater exposure assessment to be a ver y conservative screening level type approach. In the recent assessments EFED us ed the lumped DT50 for parent and three metabolites along with the Koc of the leas t soring compound to calculate exposure to groundwater. As a refinement option BCS asks EPA to use environmental fate endpoints of individual components of the residue of c oncern (DT50, Koc, formation rate in soils studies for each compound separately) in exposure modeling with PRZM-GW to

calculate concentrations of individual components of the residue and to sum up subsequently to obtain realistic worst-ca se exposure concentra tion of the TTR.”

EFED’s response: Assumptions employed in drinking water modeling ar e intentionally conservative in the face of data uncertainty and natural vari ability, and the agency’s regula tory mandate to minimize what might be thought of as “type II” or false-negative errors ( e.g ., failing to detect a problem where

1 US EPA 2015 Registration Review: Draft Problem Formulation for Environmental Fate, Ec ological Risk, and Endangered Species, and Human Health Drinking Water Exposure Assessments for Spiromesifen (PC Code 024875; DP Barc ode 427622). From: A. Sayer and K. Milians,

Environmental Fate and Effects Divisi on; To: J. Bloom and J. Stokes, Pest icide Re-evaluation Division; 02/20/2015.Page 3 of 3 one actually exists) at the expense of type I or fa lse-positive errors. Unfortunately sufficient fate information is not currently available to permit m odeling of spiromesifen degradates as separate,

individual entities 

### (degradation studies using the residues of concern as test materials are not available) . The total toxic residue approach was thus used instead, to represent summed residues of concern in ground and surface water. Refinement s to this approach may be considered in the future, subject to availability of the necessary fate information (degradation rates, sorption coefficients) on individual degradates.